Continuous variable transmission (CVT) mechanism is applied to a motor vehicle for the purpose of improving the fuel efficiency of the motor vehicle. A lubricating oil for the CVT may be referred to as a continuous variable transmission fluid (CVTF).
A lubricating oil composition containing a lubricant oil base oil, an imide compound, an amide compound, and an aliphatic amine compound wherein the content of the imide compound is 300 to 1,000 ppm by mass in terms of nitrogen based on the total amount of the composition; the content of the amide compound is 380 to 1,300 ppm by mass in terms of nitrogen based on the total amount of the composition; and the content of the aliphatic amine compound is 35 to 360 ppm by mass in terms of nitrogen based on the total amount of the composition is disclosed in Patent Literature 1, for the purpose of providing a lubricating oil composition capable of achieving both a high transmission torque capacity and a transmission shock preventing property in engagement of a clutch in an automatic transmission such as a multistage transmission or a continuous variable transmission.
A lubricating oil composition containing a lubricating base oil, an oil-soluble source of phosphorus, and a defined polyalkylene polyamine-based friction-improving agent reacted with an acylating agent which converts at least one secondary amino group into an amide is disclosed in Patent Literature 2, for the purpose of providing an additive composition useful for providing a lubricating oil, specifically a transmission fluid, for example, an automatic transmission fluid (“ATF”), a continuous variable transmission fluid (“CVTF”), and a double-clutch transmission fluid (“DCTF”) with excellent friction stability, and more specifically, useful for providing the transmission fluid with an excellent friction characteristic during high-speed clutch engagement.
A lubricating composition for lubricating a continuously variable transmission, containing a mixture of a major amount of a lubricating oil and an effective amount of a combination of performance enhancing additives containing: (a) at least one organic phosphite; (b) at least one amine salt of an organic phosphate; and (c) one or more friction modifiers selected from the group consisting of (1) an amide, (2) a succinimide, and (3) an ethoxylated amine is disclosed in Patent Literature 3.
A lubricating oil composition for a continuous variable transmission in which (A) Ca salicylate, (B) a phosphorus antiwear agent, (c) a friction modifier, and (D) a dispersion-type viscosity index improver are contained in a lubricating base oil containing a mineral oil and/or a synthetic oil is disclosed in Patent Literature 4, for the purpose of providing a lubricating oil composition for a continuous variable transmission which achieves both a high intermetallic friction coefficient required for a belt type CVT fluid and a shudder-preventing property to a slip control mechanism and can be used for a long term.
A lubricating oil composition for a metal belt type continuous variable transmission in which a phosphorus compound having a specific structure or a derivative thereof is contained in an amount of 0.005 to 0.1% by mass as phosphorus element amount based on the total amount of the composition in a lubricating oil base oil containing a mineral base oil and/or a synthetic base oil, to enable the achievement of a high intermetallic friction coefficient between a belt and a pulley and to have an excellent transmission characteristic is disclosed in Patent Literature 5.